Conventionally, technology for reducing the number (particulate number (PN)) of particulate matters (PM) included in exhaust gas has been developed in the auto industry, for example. As conventional technology, technology for improving a spraying characteristic of fuel injected from a fuel injection valve disposed in an internal combustion engine or reducing force of the fuel injection to suppress the fuel injected into a combustion chamber of the internal combustion engine from adhering to a wall surface is known. Particularly, as technology for reducing the force of the fuel injection, technology for dividing fuel necessary for one combustion stroke into fuel for a plurality of combustion strokes, injecting (multi-step injection) the fuel, and reducing a fuel injection amount for each combustion stroke is suggested.
However, in the case in which the fuel is injected from the fuel injection valve to the combustion chamber of the internal combustion engine, even though each fuel injection valve is driven by the same injection pulse (drive pulse to control opening/closing of the fuel injection valve) as illustrated in an upper diagram of FIG. 22, a movement of a valve element of each fuel injection valve varies on the basis of a spring characteristic or a solenoid characteristic of each fuel injection valve and a valve opening start time or a valve closing completion time of each fuel injection valve and a time width from valve opening start to valve closing completion vary as illustrated by a lower diagram of FIG. 22. That is, an injection amount of the fuel injected from the fuel injection valve to the combustion chamber of the internal combustion engine varies for each individual, according to an injection characteristic based on the spring characteristic or the solenoid characteristic of each fuel injection valve. In addition, a variation amount of the fuel injection amount is almost constant, regardless of the injection amount of the fuel injected from each fuel injection valve. For this reason, for example, when the fuel injection amount for each combustion stroke is reduced by the multi-step injection as described above, there is a problem in that a ratio of the variation amount to the fuel injection amount for each combustion stroke relatively increases and the injection amount of the fuel injected in one combustion stroke greatly deviates from a target fuel injection amount.
For the problem, technology for detecting a change of an operating state of an electromagnetic actuator configuring the fuel injection valve to change the injection pulse of each fuel injection valve according to the injection characteristic of each fuel injection valve so as to control the injection amount of the fuel injected from each fuel injection valve is disclosed in PTL 1.
A detection method disclosed in PTL 1 is a method of detecting the change of the operating state of the electromagnetic actuator from inductance of a predetermined time, in the electromagnetic actuator including an electromagnet having the inductance and a movable element controlled by the electromagnet. For example, the detection method is a method of detecting that the operating state of the actuator changes, when the inductance increases/decreases, when an inclination of a measurement value of a current passing the electromagnet changes, and when a current measurement pattern of the current passing the electromagnet and at least one of current evaluation patterns prepared previously are matched.